Recently, many technologies for an optical probe have been proposed, and generally focused on a method of scanning an optical probe. That is because, since a core technology for an optical probe lies in a technique for scanning a sample, much research has concentrated on the development of the scanning technique. Hereinafter, optical probe manufacturing technologies based on the scanning technique will be described as follows.
A first optical probe manufacturing technology has been developed to manufacture an optical probe which changes a light path of light transmitted from an optical fiber toward a scanning mirror using a reflecting mirror, and finally controls the light path using a micro electro mechanical systems (MEMS), thereby implementing a 3D image.
Such an optical probe has an advantage in that it may simply implement an image in real time by finely controlling only the scanning mirror. However, since two mirrors should be used and aligned, the optical alignment and manufacturing process may become complex. Since MEMS is used, the manufacturing cost inevitably increases.
A second optical probe manufacturing technology has been developed to manufacture an optical probe which includes an optical lens on which a focusing lens and a reflecting mirror are attached, and moves the optical fiber front and back or rotates the optical fiber according to an external operation, thereby performing scanning.
Such an optical probe has an advantage in that it may be reduced in size because the focusing lens and the reflecting mirror are attached on the optical fiber. However, it is difficult to control the optical fiber from outside.
In particular, when the optical fiber is twisted or bent during the scanning process of the optical probe which needs to be finely controlled, an inaccurate scanning result may be obtained. In this case, a distorted image may be generated.
A third optical probe manufacturing technology has been developed to manufacture an optical probe which includes a scanning mirror attached to a small motor, and rotates the scanning mirror to perform scanning. Such an optical probe has an advantage in that, since the small motor is used to perform scanning, the optical probe may be reduced in size. However, because of the high-speed rotation of the motor, vibrations may occur in the optical probe, thereby causing an inaccurate scanning result. The use of the optical probe is limited only to a circular symmetric sample.
Since a loss of data existing between radiation angles may occur in the optical probe, it is necessary to separately perform data correction.
A fourth optical probe manufacturing technology has been developed to manufacture an optical probe which includes a scanning mirror attached to the center of a propeller, induces the rotation of the propeller by passing a fluid at a constant speed, and rotates the scanning mirror using the propeller to perform scanning.
Such an optical probe has an advantage in that it is reduced in size. However, a separate fluid supply pipe is required, and it is difficult to constantly control the speed of the fluid.
A fifth optical probe manufacturing technology has been developed to manufacture an optical probe which includes an optical fiber of which the surface is fixed by an external coating, and controls a reflecting mirror using an ultrasonic wave converter installed outside the optical fiber, thereby performing scanning.
In such an optical probe, the optical fiber should be fixed when controlling the reflecting. Therefore, a separate fixing device should be installed in the optical probe, which makes it difficult to manufacture the optical probe. Since scanning is performed by controlling only the reflecting mirror, the focal depth of a light source may differ depending on the position of the reflecting mirror.
The biggest problem of the above-described technologies lies in the scanning method for efficiently scanning a light source generated from the optical fiber. More specifically, the same focal depth (position) should be maintained depending on the position of the scanning mirror, and the scanning mirror should be stably driven when scanning is performed.
As real-time image implementation is requested for a wide area, there is a demand for the development of an optical probe capable of satisfying conditions of wide scanning range and high scanning speed.